Process for preparing resinous material and product



. Patented Aug. 16, 1938 UNITED STATES PATENT OFF-ICE PROCESS FORPREPARING RESINOUS MA TERIAL AND PRODUCT poration of Delaware NoDrawing. Application February 13, 1936,

Serial No; 63,738

7 Claims. (o1. 2s0 2)- The present invention relates to novel resinousmaterials which consist of esters of polymerized lactic acid in whichone or more of the reactive hydroxy or carboxylic groups have beenesterified.

5 These novel resins are intended-for use in plastic materials andcoating compositions basedon cellulose derivatives, as Well as for otherindustrial purposes. My invention also embraces the process of makingthese novel resins and in its broadest embodiment comprises heatingpolymerized lactic acid with an organic compound which is able to reactwith a hydroxy or a carboxy group to form. an ester, i. e., with anorganic esterifying agent.

Simple lactic acid resins are more or less hard and brittle. They alsohave a high acid value and are more or less readily susceptible tohydrolysisp The novel resinous materials of this invention are more orless plastic and form flex-- ible films and the products are much lesssusceptible to hydrolysis. It is also possible by this invention toadjust the acid number of the novel resins from a substantially neutralproduct to a product having a high acid value.

It is believed that lactic acid resins consist largely of linearpolymers having a free carboxylic group on one end and a free hydroxyl'group on the other end of the molecule. When I heat such a resin with asubstance which contains a reactive hydroxyl .or carboxyl group or both(i. e. with at least one organic esterifying agent), it is assumed thatthese groups react with the hydroxyl and/or carboxyl groups of the resinto form esters, or ethers, since water is eliminated and new resins ofdifferent properties are produced.

The esterifying agents which I react with the lactic acid resins arehydroxy compounds and carboxylic acids and hydroxy esters, preferably ofmore than 3 carbon atoms. I may also use a plurality of such agents, forinstance, an alcohol and an acid. If both such compounds are used in asingle .resin, it is sometimes desirable to add themin separate stagesso that they preferably react with the polymerized lactic acid in thedesired manner rather than with each other.

Practically all simple hydroxy compounds are suitable for modifyinglactic acid resins. Somewhat preferred are hydroxy compounds of a highboiling point above, for instance, 100 C. These hydroxy compounds may bealcohols or phenols among which I wish to mention the following ashaving been used or which could be used in preparing my novel resins:'butylalcohol, octanol,

n-dodecyl alcohol; ethylene glycol, glycerol,

sorbitol; cyclohexanol, methyl cyclohexanol, benzylalcohol; oleylandeleostearyl alcohols; hydroxy esters, such as castor oil andhydrogenated castor oil (hydroxy stearin) phenol, and

the napthols.

The acids suitable for use in the present invention are mono-carboxylicacids such as butyric acid, stearic acid, linseed oil acids, China-woodoil acids, abietic acid, benzoic acid, naphthoic acid, and especiallyhydroxy monocarboxylic acids such as castor oil acids, hydroxy stearicacid (from hydrogenated castor oil) and hydroiiybenzoic acid. Thehydroxy acids are of special benefit in that they react with both the Inpreparing my novel esterified resins, ac-

cording to this invention, I, first, as is well known for instance frommy U. S. Patent 1,995,970,

polymerize lactic acid by heating it to, for instance, 265C. andsubsequent removal of byproducts by vacuum.

It appears necessary that: a substantial polymerization of the lacticacid be effected before the esterifying agent is added to'the reactionmixture as, if the agent is added too soon after the last of the waterhas been driven oil, a mixture is obtained which contains compoundswhich are not compatible with the cellulose derivatives with which thenew resins are intended to be used and cloudy or opaquecomposiincorporated into cellulose compositions.

The desired esterifying agent is added to the tions would be producedwhen the resins are heated polymerized lactic acid and heating continuedwhereby water is split off and distilled out, with vacuum being appliedif necessary. The esterification step is preferably carried out at orabove 200 C., but the temperature depends to a certain extent upon thetype of agent used. If the agent is volatile at'the reaction temperatureI prefer to operate under reflux. It is in many instances advisable tointroduce the esterifying agent dissolved in or mixed with an inertsolvent,iorinstanee;nsphthahavin morioo'mzorcqamtaum rlvatives areeliminated.

Iiitisnotrequiredthattheilnalpmducthavewhiehthepolymericlactidchainsare!ormedlsusinghothhydroxyaddandpolyaieohdsl'l;

,uejmueeunrwagmam.lt'wls'snluhleintoi00iltoifi0o-togi0mwiththelowu-molecularweightobtainettorimtsncgimmlaurylalcohol.

'lhe'followincmmillclwllliurtherillmtrate r MII'lve-hnndredputsolmheticaddwas polymeriledto anaverasemoleeularwciahtdabout 1M,alfu'instaneedesc|ihedin'my muesm.,mtypuu mated eastcrcll) wuand heatlmocntinuedfcrihoursatfl'QJi-ilashtime.lnoldertorunovethewatertermedduracmdmamthemtesothhuhctionanddidillationci'thenqdifllahdmtheduoedpresane'atfl'aimtiialthesclvent,

naphtha was expelled and crylallinem m to dhtiil nulthe vmei. n w mum: WMmb mlllmnmdnllllmlm- 01 501, lactic acidasdeserlhedinlxamplel.

The 81001101 was added'by dissolving it in-100' parts of hi-ilashnaphtha and dropping thesolution in overa periodoi! minutes, the naphthaheingallowedtodistilloflasinExampleI. The mixture was thenreacted for 2hours at about 225' 0., and under reduced pressure at 200 C. 1

Theproduetwasasympyiiquidhavinzanadd 1 number oi 'l and an averagemoleci'ilar weight or i'rom500 m 940.Itsuseinplasticcompositionswillbedescrihedfurtheron.

a Example 1i:

500partsot acidas described in ExampleI was addedSOpartroi China-woodoilacids dissolved in cc. hi-flash naphtha. The addition required one hourand the mixture was'then heated or another hour at 255 C.205 0. Ten.

parts of glycerol was then added and heating continued an bonnet-225(L-230. 0., solvent being dropped into the flaskkcontinuously andallowed to distill oi! through'a condenser remove the water'of reaction.

The product was a resin of balsam-like consistency. 'It hasan acidnumber 0! 15 and an average molecular weight of 1840.

Izdmplc I7 v Five-hundred partsol 50% lactic acid was concentrated bydistilling oi! the water as previously described. The acidwaspolymerized by heating with stirring for one hour at 250 C. and foranother hour sit-205 C. No solvent was used in thiscase. Twenty-fiveparts of phenol was th n added and heating continued for two hours at225'C. Thetemperaturewasthendroppedto 2009C. for

ceased. Theiinalproduetwas'atouglrpla'sticreainhavingnoodom'ofi'reephenol. Ithadan acid'nui'nheroi 11'! and wassolublein alcohol.

about so minutes, atiwhichtime distillation ma .17

esters ollililacticaeid asshownhutheiaetthattheirmoleeularwe'izhts acid.v 10 Nitrocellulose 10 .Castor oil I 2 Dibutyl phthalatei; 2 Solvents(to spraying viscosity) i253 Example B Parts by weight n-Dodecyl:alcohol ester of polymerized lactic acid i Nitrocellulose" v e 5Solvents (to spraying viscosityl'- '76 Per cent Esters a 40 Alcohols 10Aromatic hydrocarbons i EzampZesC and D v I by weight, Castor oil esterof polymerized lactic acid- 10 5 Ethyl. cellulose-.'; 10 10.

cellulose in lacquers,

' Dibiityl phthalat fusion methods are used. If the esterifying agent isquite volatile (as, for example, the lower aliphatic alcohols), thepolymerization of theilactic acid is efiected in the usual manner,either using a solvent or not as desired, and are-flux condenser is thenattached for the esterification state to prevent loss of the volatilematerial, no solvent being used in' this stage. After the desired eteriflcation has taken place, the product may heated under reducedpressure for a short time. I prefer to use atemperature of 265 C. forthe polymerization of the lactic acid. While I consider this to be anoptimum temperature, it is by no means critical, and other temperaturesmay be used. The efiect ofusing a temperature lower than 265C. is toincrease the time required, while the effect, of using a highertemperature is to cause some decomposition of the acid. The temperatureused during the esterlfl cation' stage depends largely on the nature ofthe esterifying agent. I

The sters of polymerized lactic acid may "be used as the resinouscomponents of. coating compositions. They are compatible withnitrocellulose, and in certain ratios, with cellulose acetate and ethylcelluloser When combined with nitrothey give coatings which have verygood durability characteristics.

Example A v Parts by weight Castor oil acids ester of polymerized lacticA suitable'mixture of solvents for the above lacquers is as follows:

- lowing solvent mixture:

, 3 Used in solution containing 20% solids, in foln-Dodecyl ester ofpolymerized lactic acid 10 Cellulose acet 40 which consists in reactingat a temperature of at r least'225 C. polymerized'lactic acid and atleast Parts by weight Ethyl alcohol 25 Toluene 25 xylene 25 Butylalcohol- 25 Example E' one esterifying agent selected fron'rthe groupconsisting of monocarboxylic acids, phenols and alcohols, continuing thereactionuntil a substantial amount of water is formed, and removing thewater of formation. 1 i

2. The process of claimi in which the polymerized lactic acid is reactedwith an alcohol having a boiling point above 100 C.

3. The process of claim Lin which the poly- .merized lactic acid isreacted with n-dodecyl alcohol.

4. The process of claim '1 in which the polymerized lactic acid isreacted with hydro'xystearin.

5. The process of 31mm '1 in whichthe polymerized lactic acid is reabtedwith a fatty acid 1 derived from a fatty oil.-

.8. Theprocess of claim 1 in which the polymerized lactic acid isreacted with China-wood oil l acids" and thereafter with glycerol.

'1. A composition of matter obtained by reacting polymerized lactic acidwith at least one esterifying agent selected from; the group consistingof monocarboxylic acids, phenols, and alcohois'according to the processof claim 1 characterized by a diflerent molecular weight, by being moreplastic, and by being less susceptible to hydrolysis than thepolymerized lactic acid.

-- 'anorws1-. Donovan.

